The invention relates to a test station for electronic testing of semiconductor chips and the like.
A test station of the type to which the invention relates typically includes a stage on which a test object is placed for observation, a microscope for viewing the test object, a plurality of probes for making electrical contact with the test object at various points, and means for adjusting the positions of the stage, microscope and probes relative to one another. It is desirable that the mechanisms for adjusting the positions of the components be substantially free of play and lost motion to enable the operator to make precise adjustments as small as a fraction of a micron.
In the past, mechanisms for adjusting the relative positions of components in test stations have typically involved rack-and-pinion or lead screw mechanisms in combination with sliding dovetail arrangements. One disadvantage of such mechanisms is that they require precision components with extremely low tolerances which are relatively difficult and expensive to manufacture. Another disadvantage is that, over an extended period of time, particulate matter may collect in the dovetail slide channels, increasing friction between relatively-moving components. Test stations of the type to which the present invention relates are commonly used in laboratories for analysis of silicon chips, and small particles of silicon are frequently present in the laboratory environment. Collection of such particles between sliding surfaces increases friction and wear on the surfaces, thereby interfering with adjustment of components and with maintenance of precise control over the positions of the components.
Accordingly, one of the problems addressed by the present invention is the provision of precision mechanisms which can be manufactured reasonably economically and which are not overly susceptible to wear in the presence of environmental contamination.
Another consideration is the susceptibility of the test station to vibration or other minor deflections resulting from external physical disturbances. In a typical laboratory setting, where the test station is supported on a laboratory bench, very minor physical disturbances, e.g., vibrations resulting from workers walking on areas of the floor near the bench, may potentially cause vibrations of sufficient magnitude to interfere with cause severe interference with viewing, and maintenance of a high degree of precision in positioning of a test object and probe tips. Accordingly, it is desirable that the individual structural components be relatively stiff, and that they fit together in such a manner as to minimize relative displacements between the components due to externally-induced stresses and strains.
Additional considerations addressed by the present invention include the provision of structural components which can be manufactured relatively economically, and which can be assembled without unduly complicated procedures; and provision for relative ease of operation and maintenance of the test station.
A general object of the invention is to provide improved mechanisms for movably supporting and adjusting test station components. Further objects of the invention will become apparent from the following description and accompanying drawings.